For many years, there have been sealing chambers for gas and liquid containers for a wide range of applications. However, there is room for improvement in sealing chambers.
Consider for example an electrowetting cell. One example of prior art has utilized a thin stainless steel diaphragm (with an optical window adhered to it in a central axial location) folded over an electrowetting cell and a rubber membrane. This has allowed the primary seal (the rubber membrane) to remain stationary while the stainless steel diaphragm moves up and down to compensate for fluidic thermal expansion. Another prior art example includes an O-ring on top of the electrowetting cell whose compression changes to compensate for fluidic thermal expansion. Another prior art example includes two O-rings with one positioned between the electrowetting cell and a top sealing plate (may be glass or other material) and the other positioned between the outer surface of the top sealing plate and a fixed outer housing. This arrangement allows the two O-rings to compensate for fluidic thermal expansion by changing their relative amounts of compression as the pressure of the fluid pushes against the top sealing plate varying amounts. For all three of these prior art examples one of the optical surfaces is floating up and down, the upwards and downwards movement may adversely affect the optical capability of the electrowetting cell or impact the placement of other optical components used in conjunction with the cell. Moreover, prior electrowetting cells have utilized a much smaller amount of fluid located in a well and are driven within a relatively small temperature range that results in a relatively small amount of thermal expansion when compared to modern day large format electrowetting cells.
Electrowetting is a microfluidic phenomenon that modifies the shape of a liquid in relation to a surface by applying an electrical field, e.g. by applying a voltage across two electrodes. For example, if the surface is hydrophobic, the electrical field causes a change in the shape of the liquid that appears to change the wetting properties of the hydrophobic surface. If the fluid(s) in an electrowetting cell and some of the wall(s) around the fluid(s) are sufficiently transparent, the electrowetting cell may be used as an electrically controllable optic. Such optics have recently been the subject of a widening scope of light processing applications, such as variable lenses, variable prisms, optical switches, displays, etc.
Electrowetting lenses, for example, are conventionally used in the camera industry. An electrowetting cell structure for a lens for a camera application or the like, e.g., to selectively focus light input to an image sensor or to selectively control beam distribution of a flash, typically supports only beam shaping.
There have been proposals to develop variable optical prisms using electrowetting cell arrangements. An electrowetting lens may have various different shaped structures, e.g., round, square or rectangular. An electrowetting prism normally is square or rectangular. The overall working principle for either beam shaping or steering is the same—the voltage applied across the dielectric layer attracts the conducting liquid so as to change the wetting area of the cell and thus the shape of the liquid(s) in the cell.